The preferred embodiment relates generally to a differential gear mechanism and, in particular, to adjusting and securing the position of a differential bearing adjuster nut, which preloads a bearing.
In a differential gear mechanism, each laterally directed axle shaft is supported on the housing by a tapered roller bearing located between the shaft and housing. The bearing should be preloaded precisely to maximize its service life. Normally the bearing's outer race contacts an inner surface of the housing. A preload force is applied to the bearing's inner race by rotating a adjuster nut on a screw thread such that an axial inner face of the nut is forced in axial contact against the axial outer face of the bearing's inner race.
The angular position of the adjuster nut and the magnitude of the preload can unintentionally change in service if the adjuster nut becomes loosened. Consequently it has become conventional in the automotive industry to secure the angular position of the adjuster nut at its approximate ideal location using a lock tab, whose angular position is substantially fixed. A conventional lock tab engages a hole formed on the adjuster nut. However, after the adjuster nut has been used to preload the bearing, the angular position of each hole on the nut is often misaligned from the location of the lock tab. Therefore, to ensure that the lock tab will engage a hole on the adjuster nut, the angular position of the adjuster nut is changed by rotating it into alignment with the lock tab. This changes the desired magnitude of the bearing preload. Then the lock tab is forced into engagement with an appropriate hole on the adjuster nut. This procedure causes the magnitude of the bearing preload to be different from its optimal magnitude, an undesirable condition that can adversely affect the function of the axle and its service life.
There is a need to secure accurately the adjuster nut at the angular position that precisely preloads the bearing such that the corresponding service life of the differential mechanism is optimal.